[Proj] Projecting a rectangle to another coord. system?

Ed McNierney ed at topozone.com
Fri Sep 10 08:06:08 EDT 2004

```Michael -

Glynn's response is right on the mark.  But are you asking a really
general question, or do you have specific values for A and B?  If A and
B come from a relatively limited list (rather than needing to support
ANY arbitrary projection) the job, and Glynn says, can be made much
simpler or even trivial.

- Ed

Ed McNierney
President and Chief Mapmaker
TopoZone.com / Maps a la carte, Inc.
73 Princeton Street, Suite 305
North Chelmsford, MA  01863
Phone: +1 978 251-4242   Fax: +1 978 251-1396

-----Original Message-----
From: proj-bounces at xserve.flids.com
[mailto:proj-bounces at xserve.flids.com] On Behalf Of Mikael Rittri
Sent: Friday, September 10, 2004 5:20 AM
To: proj at xserve.flids.com
Subject: [Proj] Projecting a rectangle to another coord. system?

Hello,
I am new to this list.

My problem is:
- I have a rectangle given in coordinate system A
(defined by its southwest and northeast corners).
- In coordinate system B, I need to find one, or possibly
two, rectangles that cover all of the original rectangle.
The new rectangle(s) don't have to be as small as possible,
although this would be nice.  (They shouldn't be much too
large, though.)
(By a "coordinate system", I mean a geodetic datum plus a projection.)

Can proj4 (or some other tool) solve this problem in the general case?

I would also be interested in the algoritms used. Do you know any paper
that has been published?

(The motivation is, of course, that a GIS system displays data in
coordinate system A, but the data is stored in coordinate system B,  so
the bounding box in A (defined by the window limits) must be  translated
to one or two query rectangles in B, for the geo-database.)

Best regards,
Mikael Rittri

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